Helical cam device and method

ABSTRACT

A helical cam device for use with a wide variety of applications generally includes a first cam component, a second cam component and an axial guide. The cam components each have a helical cam track located on an axial end, so that coaxial alignment of the two cam components allows opposing cam tracks to contact and rotate against each other. The helical cam tracks, which are preferably divided into quadrant sections, are designed such that relative rotational movement between the cam components causes a corresponding relative axial movement. According to one embodiment, the axial guide is a cylindrical rod passing through the center of the cam components; in another embodiment, it is a cylindrical sleeve surrounding the cam components. Moreover, barrel slots, detents and/or truncated peaks can be used to control the travel of the cam components.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of copending U.S. application Ser.No. 11/037,419 filed Jan. 18, 2005, and this application claims thebenefit of U.S. Provisional Application Nos. 60/537,736, filed Jan. 20,2004; 60/545,009, filed Feb. 17, 2004; 60/567,621, filed May 3, 2004;and 60/603,919, filed Aug. 24, 2004.

TECHNICAL FIELD

The present invention relates generally to cams, and more particularly,to cam devices having at least two cam components generally coaxiallyaligned such that opposing cam surfaces can convert rotational movementinto axial movement, and vice-versa.

BACKGROUND OF THE INVENTION

Cams and cam surfaces have been employed in a wide variety ofapplications, including hinges, valves, mechanical switches,carburetors, transmissions, metal forming machines and internalcombustion engines, to name but a few. Furthermore, they have been builtaccording to a broad range of designs. Some designs have a cam surfaceat an axial end of a cam component, while others have a cam surfacealong a portion of the longitudinal length of the cam component. In mostcases, movement by a first cam component causes a resultant movement inone or more second cam components.

One example of an application using a cam device is shown in U.S. Pat.No. 3,955,241, issued May 11, 1976 to Little. This patent discloses acounterbalance hinge mechanism for a cabinet lid that includes astationary hinge rod for rotatably supporting a pair of lid mounting cammembers, and slidably supporting a pair of non-rotatable cam followers.An adjustable spring assembly serves to bias the cam followers intoengagement with the cam members, in order to counterbalance gravityinduced torque effects of the lid throughout a substantial portion oflid opening movement.

SUMMARY OF THE INVENTION

In accordance with one embodiment, there is provided a helical camdevice having first and second cam components and an axial guide. Thefirst cam component has an axial end with a first helical cam track, thesecond cam component has an axial end with a second helical cam track,and the axial guide maintains the cam components in a generally coaxialalignment. The first and second helical cam tracks contact each otherand convert relative rotational movement between the cam components intorelative axial movement.

In accordance with another embodiment, there is provided a helical camdevice having first and second cam components and an axial guide. Thefirst cam component has a smooth cylindrical surface and an axial endwith a first helical cam track, the second cam component has a smoothcylindrical surface and an axial end with a second helical cam track,and the axial guide maintains the first and second cam components in agenerally coaxial alignment and has a smooth cylindrical surface. Thefirst and second helical cam tracks contact each other and convertrelative rotational movement between the cam components into relativeaxial movement so that at least one of the smooth cylindrical surfacesof the first and second cam components slides along the smoothcylindrical surface of the axial guide.

In accordance with another embodiment, there is provided a method forconverting rotational movement into axial movement. The method includessteps for (a) providing a first cam component with a first helical camtrack, (b) providing a second cam component with a second helical camtrack, (c) providing an axial guide, and (d) applying either arotational or an axial force to at least one of the cam components,wherein the rotational force causes a relative axial movement betweenthe cam components, and the axial force causes a relative rotationalmovement between the cam components.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of this invention willbe apparent from the following detailed description of the preferredembodiments and best mode, the appended claims and the accompanyingdrawings, in which:

FIG. 1 is a perspective view of an embodiment of a helical cam device;

FIG. 2 is a plan view of a portion of the helical cam device of FIG. 1,taken along lines 2-2 with the axial guide removed;

FIG. 3 is a side view of the helical cam device portion of FIG. 2, takenalong lines 3-3;

FIG. 4 is another side view of the helical cam device portion of FIG. 2,taken along lines 4-4;

FIG. 5 is a perspective view of another embodiment of a helical camdevice;

FIG. 6 is a plan view of a portion of the helical cam device of FIG. 5,taken along lines 6-6;

FIG. 7 is a side view of the helical cam device of FIG. 5, and showssome interior features of the device in phantom, and;

FIG. 8 is a side view of another embodiment of a helical cam device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, there is shown an embodiment of a helical camdevice 10 that can be used in a wide variety of applications including,but certainly not limited to, hinges, metal forming equipment, robotics,specialized drilling equipment, valves, mechanical switches,carburetors, transmissions, internal combustion engines, etc. Helicalcam device 10 generally includes a first cam component 12, a second camcomponent 14 and an axial guide 16, and is designed such that relativerotational movement R between the two cam components causes them toundergo a corresponding relative axial movement A. According to a firstembodiment, first cam component 12 is stationary, second cam component14 is movable, and both cam components are aligned in a generallycoaxial alignment. Moreover, first and second cam components 12 and 14are mirror images of one another, thus the following explanation offirst cam component 12 applies to second cam component 14 as well.

Referring now to FIGS. 1-4, first cam component 12 is preferably ametallic component having an exterior surface 20, an interior surface 22that defines an axial bore 24, a first axial end 26 with a helical camtrack 28, a second axial end 30, and an annular cross-sectional shape(best seen in FIG. 2). Preferably, exterior surface 20 is a smoothcylindrical surface that is circular in cross-section, however, it ispossible for the exterior surface to have a non-circular cross-sectionalshape such that it is square, rectangular, oval, etc. Interior surface22 is also preferably a smooth cylindrical surface that is coaxial withexterior surface 20 and defines an axial bore 24 that is sized andshaped to receive axial guide 16. Although the interior surface 22 andaxial bore 24 shown here have circular cross-sections, it is possible toprovide an axial bore having a square, rectangular, oval, or some othernon-circular cross-section. Axial bores having non-circularcross-sections can be used to limit the relative rotational movementbetween the first and/or second cam components 12, 14, which in turnlimits their corresponding relative axial movement. The thickness of thefirst cam component wall, which is the radial distance between interiorand exterior surfaces 22 and 20, is largely determined by the particulartype of application in which helical cam device 10 is being utilized,but is preferably in a general range of 3 mm-200 mm.

First axial end 26 has a helical cam track 28 and is spaced from theflat-ended second axial end 30. Like the wall thickness, the axiallength of first cam component 12 primarily depends on the particularapplication in which helical cam device 10 is being used, but ispreferably in a general range of 15 mm-1,000 mm. Helical cam track 28 isdesigned to interact with a complementary cam track located on anopposing axial end of second cam component 14, such that relativerotational movement between the two cam components results in acorresponding relative axial movement. Helical cam track 28 generallyincludes four quadrant sections 40-46 (best seen in FIG. 2) which arerespectively separated by four transition sections 48-54. Each quadrantsection has a circumferential extent of approximately 90° and is arrangesuch that adjoining quadrant sections (sections 40 and 42, sections 42and 44, sections 44 and 46, and sections 46 and 40) are inclined in agenerally opposite manner from one another. For instance, quadrantsection 40 is upwardly inclined from transition sections 54 to 48, whileadjoining quadrant section 42 is downwardly inclined in the samedirection from transition sections 48 to 50. Opposing quadrant sections(sections 40 and 44, sections 42 and 46), on the other hand, areinclined in a generally equivalent manner. For example, opposingquadrant sections 40 and 44 are both upwardly inclined when consideredin the same clockwise direction. This arrangement of alternatinginclined quadrants results in a cam track 28 that is up and down as onecircumferentially moves around the cam track. Transition sections 48-54are preferably rounded sections of the cam track 28 that transition fromone quadrant to another. More specifically, transition sections 48 and52 are preferably rounded peaks, where transition sections 50 and 54 arepreferably rounded valleys.

Each of the quadrant sections 40-46 includes a section of cam track 28that exhibits certain characteristics, including radial alignment,circumferential continuity and arrangement according to a helicalformula. The radial alignment is best demonstrated in FIG. 1, whereseveral radial lines 60 are shown extending at a perpendicular angle toa longitudinal axis 62. Each of these radial lines 60 contacts thesurface of helical cam track 28 along the entire radial thickness of thecam track; put differently, each radial line 60 is parallel to and lieson the helical cam track surface. Accordingly, any two points located onhelical cam track 28 that fall along the same radial line 60 are locatedat the same axial position.

With respect to the circumferential continuity, each quadrant section40-46 preferably extends in a continuous manner across its approximately90° such that there are no abrupt discontinuities. This continuityprovides for smooth rotational movement between first and second camcomponents 12 and 14, as an abrupt disconnect in the cam track couldimpede rotation of one or more of the cam components. It is possible tointentionally provide a disconnect, such that cam components 12 and 14could only be rotated to a predetermined position, at which point thedisconnect would act as a stop and prevent further rotation.

As for the helical formula, each quadrant section 40-46 preferably has acam track section that follows a helix; that is, for approximately 90° acam track section can be explained in terms of a single helical formula.Using Cartesian coordinates (x, y, z) and referring to FIG. 2, eachsection of helical cam track 28 can generally be expressed by thefollowing mathematical relationships:x=r*cos(α);y=r*sin(α), and;z=p*α;wherein (r) refers to the radius of the helical cam surface, (p) refersto the pitch (change in z dimension per rotation) of the helix, and αrefers to the particular angle of the helical cam track being measured.

As an example, consider a helical cam track that has a radius (r)=20 mmand a pitch (p)=15 mm/360°, and begins at a starting point correspondingto a point (a)=(20 mm, 0 mm, 3.75 mm). According to this particularexample, the starting point (a) coincides with transition section 48,which happens to be a peak on cam surface 28 (this is why thez-coordinate is 3.75 mm and not 0 mm). If one were to move 30° in thecounterclockwise direction (angle α₁) to a point (b), then thecoordinates would be as follows: x=20 mm*cos(30°)=17.32 mm, y=20mm*sin(30°)=10 mm, and z=3.75−(15 mm/360°)*30°=2.5 mm. The z-coordinateis subtracted from the initial starting elevation of 3.75 mm becausequadrant 40 is declining in the counterclockwise direction. Using thesame example, the coordinates of helical surface 28 at an angle α₂ whichequals 60° and corresponds to a point (c) are: x=20 mm*cos(60°)=10 mm,y=20 mm*sin(60°)=17.32 mm, and z=3.75−(15 mm/360°)*60°=1.25 mm. The sameformulas apply to the entire cam surface of quadrant section 40. At anangle of 90° (corresponding with transition section 54), the coordinatesof a point (d) are: x=20 mm*cos(90°)=0 mm, y=20 mm*sin(90°)=20 mm, andz=3.75−(15 mm/360°)*90°=0 mm. Accordingly, point (a)=(20 mm, 0 mm, 3.75mm), point (b)=(17.32 mm, 10 mm, 2.5 mm), point (c)=(10 mm, 17.32 mm,1.25 mm) and point (d)=(0 mm, 20 mm, 0 mm).

Because helical cam track 28 includes four quadrant sections thatreciprocate up and down and is not a single helical structure, like athread on a screw, the cam track preferably has four similar butdifferent z-coordinate equations. As explained above, the z-coordinateequation for quadrant section 40 is z=z₀−p*α (where z₀ is starting zvalue at 0°). The z-coordinate equations for the remaining quadrantsections 46, 44 and 42 are: z=z₁+p*(α−90°) (z₁ is starting z value at90°), z=z₂−p*(α−180°) (z₂ is starting z value at 180°), andz=z₃+p*(α−270°) (z₃ is starting z value at 270°), respectively. Ofcourse, the starting point (a)=(20 mm, 0 mm, 3.75 mm) could be a pointother than transition section 48, as that point is only an arbitraryframe of reference. For instance, point (d) or transition section 54could be used as a starting point such that all angles α are measuredtherefrom; in which case, the z-coordinate equations for each of thequadrants would differ from those provided above. Also, the pitch,radius, starting z values, etc. could differ from the exemplaryselections used above.

Axial guide 16 is preferably a smooth, cylindrical rod that is shapedand sized to be received within the axial bores of both cam components12 and 14. According to this embodiment, first cam component 12 isnon-rotatably attached to axial guide 16 such that no relativerotational movement occurs, wherein second cam component 14 is coupledto the axial guide so that it can rotate thereabout. The length of axialguide 16 largely depends upon the particular application in which thehelical cam device is being used.

In operation, helical cam device embodiment 10 is designed such thatrelative rotational movement R between cam components 12 and 14 causesthem to undergo a corresponding relative axial movement A, andvice-versa. In the example where a spring (not shown) is used to axiallybias the two cam components 12 and 14 together, rotation of second camcomponent 14 causes the two cam components to move with and against atorque created by the axial compression force of the spring and theshape of the opposing cam tracks. Whether the induced torque encouragesor discourages such rotation is dependent on the relative position ofthe two cam components. For instance, when helical cam device 10 is inthe orientation shown in FIG. 1 (peak to peak), the axial compressionforce exerted by the spring and the shape of the opposing cam tracksinduces a torque on the rotatable second cam component 14. This torqueencourages second cam component 14 to rotate about 90° in either theclockwise or counter-clockwise direction until there is an angularalignment of opposite cam track sections (peak to valley). At such anangular alignment, there is a minimum axial spacing or separationbetween cam components 12 and 14, and the torque that was encouragingthe second cam component 14 to rotate is gone. In order for second camcomponent 14 to rotate an additional 90° in the clockwise direction, itmust overcome a torque created by the spring force and the shape of theopposing cam tracks that is now discouraging rotation, as opposed toencouraging it. This can be further explained by the fact that a maximumaxial spacing or separation occurs between the two cam components whenthere is an angular alignment of equivalent cam track sections (peak topeak); a maximum axial separation that results in a maximum compressionof the spring. Thus, the torque caused by the spring and theconfiguration of the opposing cam tracks and exerted on the rotatablesecond cam component 14 reverses every 90° or so of relative rotationalmovement. Of course, helical cam device 10 can be operated in aclockwise and/or a counterclockwise orientation.

It should be recognized that the shape of the helical cam tracks cause adesirable balanced heeling effect during rotation of the two camcomponents. When the two cam components are being rotated against aninduced torque, as described above, the opposing helical cam trackscontact each other and produce a balanced heeling effect that causes theinduced torque to periodically reverse in direction. For example, wherethe two cam components are in a peak to valley alignment and arotational force is applied against the induced torque, the helical camtracks contact each other over a large contact surface that generallyincludes the entire radial width or thickness of each cam track, as wellas a substantial portion of the circumferential extent of each cam tracksection involved. By distributing the force that compresses the two camcomponents together, as opposed to having one cam track ride on the edgeof another, for instance, a smoother, balanced rotation is achieved.Moreover, this balanced heeling affect occurs not only in the twoopposing cam tracks just described, but also in a pair of opposing camtracks located approximately 180° away. For example, if cam tracksections 40 and an opposing section of second cam component 14 werecontacting each other, then a balanced heeling effect would also beoccurring in cam track sections 44 and the opposing section of camcomponent 14.

Turning now to FIGS. 5-7, an alternative embodiment 100 of the helicalcam device is shown having a first cam component 112, a second camcomponent 114 and an axial guide 116. The first and second camcomponents are largely the same as those previously described, thus aduplicate explanation has been omitted. The axial guide, on the otherhand, differs from that of the first embodiment in that guide 116 ispreferably a cylindrical sleeve where axial guide 16 is a cylindricalrod. Both axial guides operate in the same general manner, as they bothmaintain the first and second cam components in a generally coaxialalignment so that the second cam component can rotatably move along thecam track of the first cam component. The specific length of axial guide116 depends upon the pitch of the helical cam tracks, among otherfactors, as axial guide 116 should be long enough to fully encompassboth helical cam tracks, regardless of their relative angularorientation.

With reference now to FIG. 8, there is shown another embodiment 200 ofthe helical cam device having a first cam component 212, a second camcomponent 214, two separate axial guides 216 and 218, and a U-joint (notshown). Again, the first and second cam components are largely the sameas those previously described, however, their non-axial alignment isdifferent. The U-joint, which could be substituted for any type ofpivoting joint capable of rotatably-coupling non-axially alignedcomponents together, couples axial guides 216 and 218 together such thatcam components 212 and 214 are maintained in a non-axial alignment withan angle β formed therebetween. Preferably, angle β is in a range ofabout 0°-45°, and even more desirably is in the range of 0°-20°. Anglesgreater than about 45° can negatively impact the amount of relativeaxial travel (A) between the two cam components because they becomealmost perpendicular to one another.

Optionally, each of the previous helical cam device embodiments couldinclude one or more of the following features. First, each of the camdevice embodiments could be designed such that both cam components aremovable. In such an arrangement, first cam component 12, 112, 212 couldalso be spring loaded and move in the rotational direction (R) and/orthe axial direction (A), instead of being stationary. As will beappreciated by those skilled in the art, spring loading both camcomponents allows the total relative rotational and/or axial travelexperienced by the cam device to be divided up between the two camcomponents, as opposed to having one cam component do all of thetraveling. One of any number of ratios could be used for dividing theamount of rotational and/or axial travel between the cam components.

Second, one or more barrel slots 250, 252 (shown in phantom in FIG. 1)could be added to the first and/or second cam component for controllingthe rotational and/or axial travel of the cam components(s). In the caseof barrel slot 250, a pin or shaft 254 is attached to the axial guide16, 116, 216 such that it protrudes through slot 250. This restricts thetravel of first cam component 12, 112, 212 to rotational movement onlythrough an angular range defined by the circumferential length of barrelslot 250. Similarly, a pin or shaft 256 is attached to axial guide 16,116, 218 such that it protrudes through barrel slot 252 and only allowssecond cam component 14, 114, 214 to travel in the axial direction. Morecomplex versions and combinations of barrel slots could be used toprecisely control the path and amount of rotational and/or axial travelperformed by each of the cam components. These include helical slots,stepped slots, and larger slots in the form of openings as opposed tosimply being narrow grooves, to name but a few. Alternatively, groovesand bearings, such as ball bearings, could be used in place of thebarrel slots and pins discussed above.

Third, each of the cam device embodiments could include one or more setsof detents 270 on the helical cam track (shown in phantom in FIG. 1) forcreating a temporary stop that holds the two cam components in aspecific angular orientation. Detent 270 is a small recess in one of thehelical cam track peaks of second cam component 14 and is designed toreceive an opposing helical cam track peak of first cam component 12.When the two cam components are rotated into a particular alignment, apeak of helical cam track 28 nests within detent 270 such that the twocam components are temporarily maintained in that position and staythere until an additional force causes the cam components to rotate outof that position. Preferably, detents are provided in pairs; that is, asimilar detent (not shown) would also be provided on the other helicalcam track peak of second cam component 14 at a position that isapproximately 180° from detent 270. It is of course possible for detent270 to be located at a position other than a cam track peak, as it isalso possible for each cam component 12 and 14 to include one or moreset(s) of detents, as will be appreciated by those skilled in the art.

Fourth, each of the cam device embodiments could include one or moresets of truncated peaks 272 (shown in phantom in FIG. 1) for affectingthe axial travel during rotation of the two cam components. Truncatedpeak 272 can be a flat, rounded, or otherwise truncated feature locatedon the helical cam track of second cam component 14, and provides adwell time for the cam components during rotation. The dwell timeconstitutes a period when there is either no or very little relativeaxial travel between the two cam components, even though the they arebeing rotated. As with detents, truncated peaks 272 are preferablyprovided in pairs, and can include any combination of flat, rounded, orother appropriate shaped features.

It will thus be apparent that there has been provided in accordance withthe present invention a helical cam device, as well as a method ofoperation which achieve the aims and advantages specified herein. Itwill of course be understood that the foregoing description is only ofpreferred exemplary embodiments, and that the invention is not limitedto the specific embodiments shown. For example, it is possible for axialends 26 and 30 of stationary cam component 12 to each have helical camtracks so that they each interact with another cam component. In such anarrangement, a total of three or more cam components could be generallycoaxially aligned. It is also possible to provide a cam component whereone or more, but not all, of the quadrant sections are aligned in theradial direction, continuous throughout their circumferential extent,and/or are arranged according to a helical formula. Likewise, it ispossible for two or more quadrant sections to have differingcircumferential extents and/or different helical formulas (differentpitch, radius, starting z-value, etc.). Also, the helical cam devicecould be designed such that a spring biases the two cam components awayfrom each other, as opposed to the examples provided above where thespring biases them towards each other. Various changes and modificationswill become apparent to those skilled in the art and all such variationsand modifications are intended to come within the scope of the appendedclaims.

1. A helical cam device, comprising: a first cam component having anaxial end with a first helical cam track and having an opposite axialend; a second cam component having an axial end with a second helicalcam track and having an opposite axial end, wherein the axial ends withthe helical cam tracks face each other and the opposite axial ends faceaway from each other; and an axial guide for maintaining said first andsecond cam components in a generally coaxial alignment, wherein saidfirst and second helical cam tracks contact each other along matinghelical surfaces and convert relative rotational movement between saidcam components into relative axial movement, the mating helical surfacesbeing configured to distribute forces pressing the two cam componentstogether over the mating helical surfaces during relative movement. 2.The helical cam device of claim 1, wherein at least one of said firstand second helical cam tracks includes a plurality of quadrant sectionsarranged such that adjoining quadrant sections are inclined in agenerally opposite manner, and opposing quadrant sections are inclinedin a generally equivalent manner.
 3. The helical cam device of claim 2,wherein said quadrant sections are separated by rounded transitionsections.
 4. The helical cam device of claim 1, wherein during relativerotation of said first and second cam components, said first and secondhelical cam tracks contact each other and produce a balanced heelingeffect that causes an induced torque to periodically reverse indirection.
 5. The helical cam device of claim 1, wherein said first andsecond cam components each includes an axial bore for receiving saidaxial guide, said axial guide being a cylindrical rod.
 6. The helicalcam device of claim 5, wherein each of said first and second camcomponents has a generally annular cross-section with a wall thicknessin the range of 3 mm-200 mm.
 7. The helical cam device of claim 1,wherein said axial guide is a cylindrical sleeve that includes an axialbore for receiving said first and second cam components.
 8. The helicalcam device of claim 1, wherein said first cam component is attached tosaid axial guide such that it is stationary and said second camcomponent is coupled to said axial guide such that it is movable.
 9. Thehelical cam device of claim 1, wherein said first and second camcomponents are both coupled to said axial guide such that they are bothmovable.
 10. The helical cam device of claim 1, wherein at least one ofsaid first and second cam components includes a barrel slot forreceiving a pin.
 11. The helical cam device of claim 1, wherein at leastone of said first and second helical cam tracks includes a detent. 12.The helical cam device of claim 1, wherein at least one of said firstand second helical cam tracks includes a truncated peak.
 13. The helicalcam device of claim 1, wherein at least one of said first and secondhelical cam tracks includes a quadrant section that is: i) aligned in aradial direction, ii) continuous throughout its circumferential extent,and iii) arranged according to the following formulas:x=r*cos(α);y=r*sin(α); andz=p*α; wherein x, y and z represent coordinates of a point lying on saidhelical cam track(s), r represents a radius of said helical camtrack(s), p represents a pitch of said helical cam track(s), and αrepresents an angle relating to said point.
 14. A helical cam device,comprising: a first cam component having a smooth cylindrical surfaceand an axial end with a first helical cam track; a second cam componenthaving a smooth cylindrical surface and an axial end with a secondhelical cam track; and an axial guide for maintaining said first andsecond cam components in a generally coaxial alignment and having asmooth cylindrical surface, wherein said first and second helical camtracks contact each other along mating helical surface portions at aplurality of separate angular locations and convert relative rotationalmovement between said cam components into relative axial movement sothat at least one of said smooth cylindrical surfaces of said first andsecond cam components slides along said smooth cylindrical surface ofsaid axial guide; and wherein two of the mating helical surface portionsare angularly spaced from each other by about 180 degrees and areconfigured to produce a balanced heeling effect with smooth and balancedmovement.
 15. The helical cam device of claim 14, wherein said at leastone smooth cylindrical surface of said first and second cam componentsis an interior surface that forms an axial bore for receiving said axialguide.
 16. The helical cam device of claim 14, wherein said at least onesmooth cylindrical surface of said first and second cam components is anexterior surface that is received within a bore of said axial guide. 17.A method of converting rotational movement into axial movement,comprising the steps of: (a) providing a first cam component having afirst helical cam track; (b) providing a second cam component having asecond helical cam track; (c) providing an axial guide for maintainingsaid first and second cam components in a generally coaxial alignment sothat said first and second helical cam tracks contact each other; and(d) applying either a rotational or an axial force to at least one ofsaid cam components so that said first and second helical cam trackscontact each other along mating helical surfaces that are configured todistribute said rotational or axial force over the mating helicalsurfaces and produce a balanced heeling effect, wherein said rotationalforce causes a relative axial movement between said cam components, andsaid axial force causes a relative rotational movement between said camcomponents.